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From Wikipedia, the free encyclopedia

Lycopsis longirostris, an extinct metathere from the Sparassodonta, a sister taxon to the marsupials
Scientific classification
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Theria
Infraclass: Metatheria
Thomas Henry Huxley, 1880
Orders and infraclasses

Metatheria is a grouping within the animal class Mammalia. First proposed by Thomas Henry Huxley in 1880, it is nearly synonymous with the earlier taxon Marsupialia (Illiger, 1811) though it is slightly wider since it also contains the nearest fossil relatives of marsupial mammals.

The earliest known representatives are from the uppermost Lower Cretaceous of North America.

The closest relatives of the metatheres are the Eutheria (also erected by Huxley in 1880). Both are conventionally united as infraclasses within the subclass Theria (Parker and Haswell, 1897), which contains all living mammals except monotremes.

During development, metatherians produce a yolk sac placenta and give birth to "larval like" offspring. These offspring have under developed posterior limbs (the pes can be webbed), and following birth they migrate to the marsupium where they attach to a nipple. The mouth of newly born metatherians is fused laterally, but open medially; this forms an "O" shaped mouth in which the mothers nipple fits, then swells to secure the offspring into place for further development and growth.

The Greek words meta- and theria roughly means the "other beasts", in contrast with Eutheria ("true beasts").

Evolutionary history

Metatherians first appeared in the Cretaceous Period, with such forms as Deltatheridium and Asiatherium. Some stem metatherians persisted well into the Paleogene Period before becoming extinct. Examples of these include the borhyaenids and herpetotheriids. crown marsupials, the one branch of Metatheria that survives today, diversified close to the time of extinction at the end of the Cretaceous.[1]

See also


  1. ^ Horovitz, Inés; Martin, Thomas; Bloch, Jonathan; Ladevèze, Sandrine; Kurz, Cornelia; Sánchez-Villagra (2009). "Cranial Anatomy of the Earliest Marsupials and the Origin of Opossums". PLoS ONE 4 (12): e8278. doi:10.1371/journal.pone.0008278.  
  • McKenna MC & Bell SK, (1997), Classification of Mammals Above the Species Level. Columbia University Press.


Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary




From Ancient Greek μετά (meta), changed) + θηρίον (thērion), beast).

Proper noun

Wikipedia has an article on:



  1. a taxonomic infraclass, within subclass Theria - the marsupials
Wikispecies has information on:


See also


Up to date as of January 23, 2010

From Wikispecies


Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Metatheria


Metatheria Huxley, 1880

Vernacular names

Español: Metaterios
한국어: 후수하강
Italiano: Metateri
日本語: 後獣下綱
Polski: Ssaki niższe
Русский: Сумчатые
Українська: Сумчасті
Wikimedia Commons For more multimedia, look at Marsupialia on Wikimedia Commons.

Simple English

Redirecting to Marsupial


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